chap, iv.] THE ORBIT AND EYE. 57 



or intolerance of light, is common in inflammatory 

 affections of the eye. In this condition there is spasm 

 of the orbicular muscle, keeping the eye closed, or 

 closing it on the least exposure to irritation. Here 

 the nerve most active is the branch of the facial to 

 the orbicularis, and the reflex irritation reaches that 

 nerve either through the branches of the fifth in the 

 cornea and conjunctiva, or through the disturbed 

 optic nerve. Photophobia is most marked in super- 

 ficial affections of the cornea, and is often much 

 benefited by a seton in the temporal region. This 

 acts apparently by counter - irritation of another 

 division (the second) of the fifth nerve supplied to 

 the region of the temple. The relations between 

 the nasal nerve and the orbital contents receive 

 many illustrations in practice. Thus, if the front 

 of the nose be struck, or the skin over its lower 

 part be irritated, as by squeezing a painful boil, 

 profuse lachrymation will frequently be produced. 

 Snuff, too, by stimulating the nasal branch of the 

 ophthalmic nerve, often makes the eyes of the un- 

 initiated to water ; and it is well known that there are 

 many disturbances about the nose, and the anterior 

 part of the nasal fossae, that can " make the eyes 

 water." Herpes zoster often provides a remarkable 

 illustration of the intimate relation between the nasal 

 nerve and the eye. In this affection, when the regions 

 of the supraorbital and supratrochlear branches of the 

 first division are alone implicated, the eye is usually 

 unaffected ; but when the eruption extends over the 

 part supplied by the nasal nerve, i.e. runs down the 

 side of the nose, then there is very commonly some 

 inflammation of the eye-ball. In frontal neuralgia 

 watering of the eye (irritation of the lachrymal branch) 

 is very frequently met with. 



The dangerous area of the eye. Pene- 

 trating wounds of the cornea alone, or of the sclerotic 



